CEREBRAL OXYGENATION AND BLOOD VOLUME TRENDS DURING GRADED EXERCISE IN HEALTHY MALES
Bibliographic record
Abstract
PURPOSE It has been hypothesized that a central governor may regulate oxygen consumption during severe exercise to limit cerebral hypoxia (Noakes et al., J Exp Biol, 2001). This study examined the acute cerebral oxygenation (Cox) and blood volume (Cbv) responses of males to graded exercise in normoxia. As well, the relationships between cardiorespiratory measures, maximum power, Cox and Cbv were examined. METHODS Twenty-two healthy male volunteers completed a graded exercise test to voluntary fatigue on a cycle ergometer (2 min unloaded, 25W/min). Cardiorespiratory variables were recorded using a metabolic cart and wireless heart rate monitor. Cox and Cbv were monitored continuously from the left frontal lobe using a dual wavelength near infrared spectrometer. Delta values (max – baseline) of Cox and Cbv were calculated for each subject. RESULTS Both Cox and Cbv increased systematically with work rate, and the increase in delta Cbv was greater than the increase in delta Cox (mean ± SD = 0.515 ± 0.373 vs. 0.437 ± 0.382 OD units; P < 0.005). Although there was a significant relationship between delta Cbv and delta Cox (r = 0.729, P < 0.000), visual inspection revealed that 13 subjects displayed a linear increase in Cbv over the entire test but had a reduction in Cox in the final two workloads. Delta Cox and delta Cbv were not significantly related to VO2max or maximum power (P > 0.05). CONCLUSION An increased Cbv in our study indicates that healthy males may increase Cbv to some extent in order to maintain Cox during a graded exercise test. The observed decrease in Cox in the final two workloads of 13 subjects may be secondary to the increase in Cbv or may indicate greater oxygen utilization during these two final workloads. Alternatively, the decrease in Cox may be a cause of fatigue which limits maximal exercise in healthy subjects. This could be part of a protective mechanism for maintenance of cerebral oxygenation, i.e., when Cox starts to decline, exercise stops soon after. Supported by “Support for the Advancement of Scholarship”, University of Alberta.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".